Cinematographic apparatus



Oct. 12, 1937.

c. R. -HANNA 2,095,744

C INEMATOGRAPH I C APPARATUS Original Filed April 4. 1930 WITNESSES:

ATTORNEY Patented Oct. 12, 1937 UNITED STATES PATENT OFFICE 2,095,744CINEMATGGR-APHIC APPARATUS Grigina'l application April 4, 1930, SerialNo.

441,583. Divided and this lapplication June 19, 1935, Serial No. 27,359

7 Claims.

My invention relates to improvements in cinematographic apparatus and ithas. particular relation to intermittent movements.

The present application is a division of my copending application,Serial No. 441,583, filed April 4, 1930, and assigned to theWestinghouse Electric & Manufacturing Company.

It is an object of my invention to provide for a picture projectionsystem, an intermittent movement that shall advance the film through asmall fraction of its total period of operation.

A further object of my invention is to provide an intermittent movementof simple structure for a motion picture machine by the operation ofwhich the lm shall be advanced rapidly and shall consequently be at restduring comparatively large fractions of the total period of projectionof a frame.

Another object of my invention is to provide an intermittent movementthat shall operate quietly and that shall, therefore, be particularlyadapted for a motion picture machine that is to be utilized in the home.

According to my invention, I provide an intermittent movement comprisinga cam and a cam follower. The cam is of the peripheral heartlshapedtype. The arcs of the cam which coact with the cam follower to advancethe lm are, in contrast to those of the prior art, greater than and ingeneral of the order of 1l5.

The rapid advancement of the film is also materially aided by pivotingthe cam follower between the shaft of the cam and the claws. In priorart structures, the cam is rotated between the claws and the pivotedpoint.

Quiet operation of the apparatus is produced by providing a cam followerwhich is resiliently held in engagement with the cam. The cam ismaintained continually in engagement with the cam follower and impactsbetween the cam and the cam follower are avoided.

I'he novel features that I consider characteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization 4and its method ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of a specificembodiment, when read in connection with the accompanying drawing, inwhich:

Figure l is a view, in perspective, of a section of a machine wherein myimprovement is embodied;

' Fig. 2 is a view, in section, taken in the direc tion II-II of Fig. l;

Fig. 3 is a plan view, of the principal elements of the intermittentmovement of the machine;

Fig. 4 is a view, in section, taken along line IV-IV of Fig. 3;

Fig. 5 is a schematic drawing of the cam and follower, showing itsgeometric structure;

Fig. 6 is a schematic drawing of a cam and its operated 'device havingintermittent movement according to the teachings of the prior art;

Fig. '7 is a schematic drawing of a cam and" its operated device havingan intermittent movement according to my invention; and

Figs. 8, 9, 10, 11 and 12 are schematic drawings showing a plurality ofconfigurations that may be given to the cam-follower.

The apparatus shown in the drawing comprises a curved aperture plate Isupported on the main plate 2 of a cinematographic machine, on which afilm-strip is to be positioned by a plurality of tensioned shoe-straps 4and 5 and over which it is intermittently advanced by a plurality ofclaws 6 and 1.

The shoe-straps 4 and 5 are rigidly fastened to a bracket 8 pivotallysupported on a stud 9 projecting from the main plate 2 of the machine,and they are held in tension by a plurality of flat springs II fastened,at one end, to the straps and,n at the other end, to a finger I2 rivetedto the strap-supporting'bracket 8.

A knurled knob I3, pinned to a shaft (not shown) that is slidablysupported in a sleeve` I5 riveted to the bracket 8, is provided formoving the shoe straps 4 and 5 relative to the plate I. The sleeve I5 isequipped with a cavity (not shown) wherein a spring (not shown) isdisposed. The latter engages an inwardly-extending shoulder (not shown)lin the sleeve I5 and a shoulder (not shown) on the shaft and resilientlyurges the shaft into engagement with a finger 2I projecting downwardfrom a bracket 22 that supports a projection lens 23.

The projecting end of the shaft coacts with the inner end of the finger2l to hold the shoestrap bracket 8 in closed position and it reacts withthe outer end of the finger 2I to hold it in open position. By exertingan axial force on the knob I3, opposite in direction to the forceexerted by the spring, the shaft may be disengaged from the bracket 2I.However, when the knob is released, the shaft, if unconstrained,automatically returns to one of its engaging positions.

In the particular embodiment of my invention described herein, theintermittently-operating claws 6 and 1, in advancing the film, coactwith are ordinarily situated. Since the claws must be provided with anunobstructedpassage through the lm, the shoe strap 5, on the side of thefilm On which the engagement takes place, is dis- 4.tended and slottedinthe region where the claws traverse the lm.

',I'he intermittent movement comprises chiefly a peripheral cam 25,rigidly supported on one end of a shaft 26 that is driven through a gear27 disposed on the other end thereof, and a square frame 28 adapted tocontinually engage the periphery of the cam at a plurality of points.

A rod 29 fastened to a boss 3l integral with the square frame 28 andslidably mounted in a sleeve 32 rigidly supports the film-advancingclaws, l and motivates them as it moves under the action of the squarecam-follower 28. The sleeve is fastened to a boss 35 in the main plate 2and is capable of rotating relative thereto. 'The clawsupporting rod 2,9is thus adapted to slide and pivot under the action of the cam 25.

A cover 36, equipped with an opening for the claw-supporting rod 29;,encloses .the cam and square and prevents the lubricant disposed betweenthe surfaces from being ejected.

The geometric structure of what I define asfa peripheral cam isillustrated in Fig. 5, in which O represents the center ofthe cam shaft,AB and CD are arcs of two circles concentric with C, AC

is an arc of a curve of which B is a center and BD is an arc of a circleof and AD, which is equal toA 'BC, is the radius. To round out the sharpcorners BC is a radius, and which A is a center of the cam, theiradiiare increased by an equal amount, and the requisite fillets are addedbetween the arcs, as shown in the configuration by broken lines. 'v

In constructing the cam, the arbitrarily assigned quantities areordinarily the angle 9 between AO and OB and the maximum distance that afollower is displaced by the cam surfaces; that is OB-OC.

It is easily shown, however, that Hence OB is determined.

From the point O located on a plate of the material from which the camis constructed, the two lines OA and OB are drawn, making an angle 0with each other. With O as a. center and OB as radius, the arc AB isinscribed, with A as center at O is inscribed tangent to arcs AC and Thecams included in intermittent movements constructed according to theteachingspf the fold advantage over the older intermittent motions',wherein the cam is disposed between claws as shown in Fig. 6.

1. By a simple mathematicalconsideration, it can be shown that theradius of curvature of the trajectory described by the lower claw at itspoint of intersection with the line determined by the the shaft centerand the .pivot is defined by the equation for the device shown in Fig.6.

In this equation, ,e is the distance between the center of the pivot 38and the end of the lower claw 'l in the aforementioned position and a isthe distance between the shaft center 39 and the pivot center 38. Thecorresponding property of the claw-trajectory of Fig. 7 is dened by tSince the path traversed by a claw is small, as compared with a and ,6,it is obvious that it coins throughout its useful range with the arc ofa circle described according to EquationA (l) or Equation (2), as theconstruction may require. Hence, from Equation (2), it is seen that thearcuate path described by the claw l, in the intermittent motionprovided by my invention,

can have any predetermined curvature. That is,

thecurve can be convex with reference to the cam if is made less than a,concave with respect to the cam if is greater than a, and a straightline if ,e is equal to a.

Since it is desirable to give the aperture plate a certain curvatureand, furthermore, since the cam required by a rectilinear verticalmotion of the claws is rather large, the ratio of to a in theintermittent movement embodied in my in- Y vention is made approximatelyequal to 2.

2. It is to be noted that the edges of the camfollower 28 do not remainparallel to their original position as the follower is moved. Since thefollower is rigidly`fastened to the claw-supporting bar 29, it mustpivot about the surface of the cam 25 in accordance with the positionassumed by the rod 29. Y

In the device shown in Fig. 4, the follower has an angular motion in thesame direction as the cam, while, in the device shown in Fig. 5, the twoangular motions are opposite in direction. As is clearly seen from thisdrawing, the lowest point of contact 0 between the cam and thefolloweris, in Fig. 6, advanced beyond the analogous point for a cam anda non-pivoting follower by an angle equivalent tothe angle through whichthe sides of the follower have been rotated from its initial' position.On the other hand, the lowest contact point of a cam and a non-pivotingcam follower leads the corresponding contact point llllfor the device ofFig. 7 by a similar angle. It follows then that, for identical cams,equal distances between pivot and camshaft center, and equal totallengths for the pivoting arms, the cam shown in Fig. 6, which representsthe older movement, moves through a greater angle in advancing the filmone frame than the cam shown in Fig. '1, which represents my improvedmovement.

The advantage is of considerable importance in obtaining smallfilm-moving time with a comparatively small 'cam since the ratio offilmmoving-time to film-resting-time decreases as the angle 6 increases,while the dimensions of the cam required to give the claws apredetermine'd motion in one direction increases with 0.

In Figs. 8 to l0, various possible structures of the cam follower areshown. The structure utilized to obtain quiet operation is shown inFigs. 1l and 12. In Fig. 1l, a cam follower Wherein two sides of thesquare frame are supplanted by flat springs l is shown diagrammatically.In Fig. 6, a practical structure is illustrated. To provide thestructure shown in Fig. 6, the follower is stamped from sheet metal andthe flat springs 5l are provided by separating the sides indicated as 5lfrom the base of the cam follower. In a structure of this type, the camis held snugly in contact with the follower and the racket thatordinarily arises from a loosely fitting cam is eliminated without anyconsiderable expense.

Although I have shown and described certain specific embodiments of myinvention, I am fully aware that many modifications thereof arepossible. My invention, therefore, is not to be restricted exceptinsofar as is necessitated by the prior art and by the spirit of theappended claims.

I claim as my invention:

1. An intermittent feed for a web comprising web-moving means and meansfor engaging and disengaging said web-moving means to and from said webto intermittently advance said web including a cam the periphery ofwhich is composed of a plurality of surfaces, two of which are coaxialcircular cylindrical surfaces of different radii and on opposite sidesof the axis, said cam to be rotated about an axis that'coincides withthe axis of said circular cylindrical surfaces and said circularcylindrical surfaces subtending an angle substantially greater than 90at said axis, a cam follower tangent to said cam at a plurality ofpoints whereby it is moved when said cam is rotated, means forconnecting said web-moving means to said follower whereby saidweb-moving means is actuated by said cam follower in accordance with themotion thereof to intermittently engage, advance, and disengage saidweb.

2. Motion picture apparatus, comprising a mechanism in which a motionpicture film is interposed in the path of a light beam, film-movingmeans for advancing the lm through said mechanism and means for engagingand disengaging said film-moving means to and from said film tointermittently advance said film; the last said means including a camthe periphery of which is composed of a plurality of surfaces, two ofwhich are coaxial circular-cylindrical surfaces of different radii andon opposite sides of the axis, said cam to be rotated about an axis thatcoincides with the axis of said circular-cylindrical surfaces and saidcircular-cylindrical surfaces subtending an angle substantially greaterthan 90 at said axis, a cam follower tangent to said cam at a pluralityof points whereby it is moved when said cam is rotated and means forconnecting said film-moving means to said follower whereby saidfilm-moving means is actuated by said cam follower in accordance withthe motion thereof to intermittently enfgage, advance, and disengagesaid film.

3. Motion picture apparatus particularly adapted for use in the homecomprising a mech-Y is composed of a plurality of surfaces two of whichare coaxial circular-cylindrical surfaces of different radii, located onopposite sides of the axis, said cam to be rotated about an axis thatcoincides with the axis of said circularcylindrical surfaces,cam-following means to be moved by said cam when it is rotated, saidcamfollowing means including at least two substantially plane rigidfaces adjacent and at an angle to each other adapted to contact said camat a plurality of points, resilient means biasing said cam-followingmeans for vmaintaining both of the rigid faces of said following meansin contact with said cam continuously at a plurality of points and meansfor rigidly connecting said film-moving means to said follower wherebysaid film-moving means is actuated by said cam follower in accordancewith the motion thereof to intermittently engage, advance, andvdisengage said film.

4. An intermittent-movement mechanismcomprising a cam, the periphery ofwhich is composed of a plurality of surfaces, two of which are portionsof coaxial circular cylinders having different radii, a cam followerrigidly connected to a drive-member and comprising two substantiallyplane rigid faces adjacent and at an angle to each other substantiallyparallel to the common axis of said cylinders and adapted to engage saidcam at two separate points, resilient means on the follower formaintaining said cam follower in engagement with the surfaces of saidcam, and means for continuously revolving said cam about the common axisof said cylinders.

5. An intermittent-movement mechanism comprising a cam, the periphery ofwhich is composed of a plurality of surfaces, two of which are portionsof coaxial cylinders having different radii, a cam follower rigidlyconnected to a drive-member and comprising two substantially plane facesadjacent and at right angles to each other and parallel to the commonaxis of said cylinders adapted to engage said cam at two separatepoints, resilient means on said follower for maintaining both said facesin engagement with the surfaces of said cam, and means for continuouslyrotating said cam about the common axis of said cylinders.

6. In combination, a peripheral cam which is composed of a plurality ofsurfaces, two of which are portions of coaxial circular cylinders havingdifferent radii, and a cam follower comprising four faces parallel tothe common axis of said 'cylinders and lying in the sides of a square,the

length of each side of which is substantially equal to the sum of theradii of said circular cylinders, two adjacent members of said fourfaces being resiliently mounted relative to the other two faces.

7. An intermittent-movementmechanism comprising a cam, the periphery ofwhich is composed of a plurality of surfaces, two of which are portionsof coaxial circular cylinders having taining both of the said rigidfaces of said cam follower at all times in engagement with the surfacesof said cam, and means for continuously revolving said cam about thecommon axis of said cylinders.

CLINTON R. HANNA.

silient means biasing said cam follower for mainy

